netdev - Re: [PATCH v7 24/28] cxl: add region flag for precluding a device memory to be used for dax

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Message-ID: <1c3dc1af-a633-141b-8425-8b7f2fcbe1ca@amd.com>
Date: Fri, 13 Dec 2024 09:47:42 +0000
From: Alejandro Lucero Palau <alucerop@....com>
To: Simon Horman <horms@...nel.org>, alejandro.lucero-palau@....com
Cc: linux-cxl@...r.kernel.org, netdev@...r.kernel.org,
 dan.j.williams@...el.com, martin.habets@...inx.com, edward.cree@....com,
 davem@...emloft.net, kuba@...nel.org, pabeni@...hat.com,
 edumazet@...gle.com, dave.jiang@...el.com
Subject: Re: [PATCH v7 24/28] cxl: add region flag for precluding a device
 memory to be used for dax


On 12/12/24 18:44, Simon Horman wrote:
> On Mon, Dec 09, 2024 at 06:54:25PM +0000, alejandro.lucero-palau@....com wrote:
>> From: Alejandro Lucero <alucerop@....com>
>>
>> By definition a type2 cxl device will use the host managed memory for
>> specific functionality, therefore it should not be available to other
>> uses. However, a dax interface could be just good enough in some cases.
>>
>> Add a flag to a cxl region for specifically state to not create a dax
>> device. Allow a Type2 driver to set that flag at region creation time.
>>
>> Signed-off-by: Alejandro Lucero <alucerop@....com>
>> Reviewed-by: Zhi Wang <zhiw@...dia.com>
>> ---
>>   drivers/cxl/core/region.c | 10 +++++++++-
>>   drivers/cxl/cxl.h         |  3 +++
>>   drivers/cxl/cxlmem.h      |  3 ++-
>>   include/cxl/cxl.h         |  3 ++-
>>   4 files changed, 16 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
>> index b014f2fab789..b39086356d74 100644
>> --- a/drivers/cxl/core/region.c
>> +++ b/drivers/cxl/core/region.c
>> @@ -3562,7 +3562,8 @@ __construct_new_region(struct cxl_root_decoder *cxlrd,
>>    * cxl_region driver.
>>    */
>>   struct cxl_region *cxl_create_region(struct cxl_root_decoder *cxlrd,
>> -				     struct cxl_endpoint_decoder *cxled)
>> +				     struct cxl_endpoint_decoder *cxled,
>> +				     bool no_dax)
> nit: no_dax should be added to the Kernel doc for this function.


Yes, I'll do.


>
> Also, I think you need to squash the following patch, which updates
> the caller to use pass the extra argument, into this patch. Or otherwise
> rework things slightly to avoid breaking bisection.


Correct. Ed raised this concern as well, and I'll change the patches 
order in v8 for avoiding the problem.

Thanks!


>>   {
>>   	struct cxl_region *cxlr;
>>   
> ...
>